The invention is related to the field of thermal technology, and more specifically to cooling mobile computing systems using vapor chamber.
Electronic components from microprocessors to high-end power converters generate heat. The rejection of this heat is necessary for their optimum and reliable operation. As electronic design allows higher throughput in smaller packages, dissipating the heat load becomes a critical design factor.
There are different ways of dissipating heat. These include radiation, conduction and convection. Radiation means that the heat is simply radiated away from the object, through electromagnetic radiation. Conduction is the exchange of kinetic energy between molecules. Less energetic (lower temperature) particles gain kinetic energy by colliding with more energetic particles (through physical contact).
Convection is heat transfer by movement of a heated substance (gas or liquid). This means that the heat is transferred to the molecules of the gas (or liquid) surrounding the hot object, and then transported away through movement of molecules. When the gas or liquid around the object is forced into movement (e.g., by a fan blowing air across a heat sink), then it is forced convection. Many of today""s electronic devices require cooling beyond the capability of standard metallic heat sinks.
One cooling approach uses vapor chambers. The vapor chamber loses heat within the computing system by convection and radiation. Typically, a vapor chamber is a vacuum vessel with a wick structure lining the inside walls that is saturated with a working liquid. As heat is applied, the fluid at that location immediately vaporizes and the vapor rushes to fill the vacuum. Wherever the vapor comes into contact with a cooler wall surface, it will condense, releasing its latent heat of vaporization. The condensed fluid returns to the heat source via capillary action, ready to be vaporized again and repeat the cycle. The capillary action of the wick lining the inside walls enables the vapor chamber to work in any orientation with respect to gravity.
One disadvantage of the vapor chamber is its lack of flexibility. Also, the vapor chamber needs to be connected to the heat sink through another thermal attach which can increase thermal resistance.